Alan Cox wrote:> > > alan@lxorguk.ukuu.org.uk (Alan Cox) writes:> >> > |> > Is kmalloc guaranteed to alloc a physically contigous buffer? My exact> > |>> > |> Yes> >> > No. It is only contiguous in the kernel virtual space.> > Thats vmalloc. If you have an architecture where kmalloc blocks are> not linear to the I/O devices you'll have a very bad time making anything> work

Call me nuts, but it _really_ bothers me that experienced kerneldevelopers can have disagreements about basic stuff. I blame the lackof documentation. Where's vmalloc (and kmalloc) explained? I couldn'tfind anything in the source.

Add to that Alan's mistake this morning about phys_to_virt() etc. and Ithink we have a clear pattern: these people aren't dummies, so we can'tblame them, there just isn't adequate documentation.

This is going to bite us more and more as the developer pool getsbigger.

I'm not flaming anyone (especially someone of Alan's stature), this kindof mistake is happening repeatedly and is being made by the bestdevelopers Linux can boast. I think we _have_ to recognise theshortfalls in the current system. Undocumented source-code is fine ifyou're sure people can find documentation somewhere...

Figuring out how to use a routine by looking at other code that uses itis a BAD idea, but it's the path of least resistance (and the path tobugs).

To summarise: good developers have some wrong ideas about some of thebasic building blocks of the kernel, and it's not fair to blameindividuals. This needs fixing.

Comments?

Neilps: if ever the FUD merchants needed ammo, incidents like these areperfect.pps: i'm quite sure MS suffer from similar problems, but let's not copy'em.

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